The British Government sets up a multi-service undercover unit to begin a ruthless campaign aimed ar wreaking havoc in the ranks of the Irish Republican Army. Kidnap, torture and shoot-to-kill orders are all on the table. But the IRA has a mission of its own. Top of their agenda is the assassination of the Secretary of State for Northern Ireland. Both sides employ their best resources. Heading up the British unit is Mike Devon, their top undercover agent. He's pitted against Fergal McSweeney, the IRA's most notorious assassin. Both men clashed in an operation in Chicago ten years previously and both have the scars to show for it. A final showdown is inevitable. Standing in the middle is the RUC, trying to make sense of the upsurge of violence on their doorstep. Detective Chief Inspector Martin Vennison is out to stop both sides turning the streets of Ulster into a war zone, but he carries a more personal reason for getting involved. The IRA murdered his boss and he wants the men who did it. The action swings relentlessly from Chicago to London, and from Glasgow to Belfast, as the three sides collide in a final bloody finale in the suburbs of Dublin.